Peat-lite Medium Research Articles

Substitution of a Soilless Medium with Yard Waste Compost for Basil Transplant Production

Four experiments were conducted under greenhouse conditions in Oklahoma. Pelleted ‘Genovese’ basil (Ocimum basilicum) seeds were sown in polystyrene flats with six different blends of a peat-lite mix (PL0) and yard waste compost [YWC (this batch designated C0)] in 2012 for the first two experiments. The proportions by volume of PL0:C0 included 100%:0%, 80%:20%, 60%:40%, 40%:60%, 20%:80%, and 0%:100%. Seedling establishment was unaffected consistently, but there was a distinct decline in seedling height and dry weight between 100% PL0 and 80% PL0:20% C0, followed by smaller decreases as the percentage of compost increased in the blends. A third experiment was conducted in 2013 with a different batch of peat-lite (PL1) after the compost had aged 17 months (now designated C1). Treatments were 100% PL1, 80% PL1:20% C1, and 80% PL1:20% C1 mixed with sulfur (S) at 1, 2, or 3 lb/yard3 of blend to acidify the media. The 100% PL1 treatment delayed seedling emergence and suppressed height and dry weight relative to seedlings grown in 80% PL1:20% C1 blends. The PL1 subsequently was found to have been produced in 2010, and the wetting agent had apparently degraded. The aged 2012 compost (C1) was not inhibitory to basil seedling growth when blended at 20% with the PL1, and in fact restored utility to the PL1. The carbon:nitrogen ratio of the original 2012 compost (C0) was 10.8:1, suggesting stability. It appeared that the main reason the C0 compost was inhibitory was that mineralization was slow or immobilization occurred, causing a lack of plant-available nitrogen, especially nitrate. Treatments with S lowered pH of the media, but there were no differences in basil seedling growth between the unamended 80% PL1:20% C1 blend and blends with added S. A fourth experiment compared three peat-lite media: PL1; a batch of the same medium as PL1 that was produced in 2013 (PL2); and a different medium also produced in 2013 (PL3). Peat-lite media were either used unblended, or blended with 20% C1 or 20% C2 (a fresh batch of YWC obtained from the same facility that had produced the original C0). The unamended PL1 was again inhibitory to basil seedling establishment and development. The two “fresh” peat-lite media (PL2 and PL3) were not inhibitory and were similar to each other in performance. A blend of 80% PL2 or 80% PL3 with 20% compost produced similar (C2) or somewhat better (C1) results than were obtained with the unamended peat. We conclude that a blend of 80% peat-lite medium and 20% YWC can be used to produce basil transplants. However, producers must consider the quality of the peat-lite medium and the compost based on the age and composition of the components.

LINER DIPS FOR GROWTH REGULATION OF VIGOROUS HERBACEOUS PERENNIALS

Many vigorous herbaceous perennials need early growth regulation. Treatment at the plug stage could improve early growth control or maintain product size in the plug tray. Concise (uniconazole, Fine Americas, Inc.), is a growth regulator labeled for use on ornamental greenhouse crops in the US. We treated plugs of five herbaceous perennials with a 2-minute dip into 0, 1, 2, 3, 4 or 5 mg/L Concise the day before planting into 1.1-liter pots filled with a peat-lite medium (ornamental grasses were maintained in the plug pots). Plant height was determined at 2 week intervals after treatment (WAT). Concise reduced shoot growth in a linear or quadratic correlation for all crops except Gaillardia × grandiflora ‘Goblin’ which was not affected by the treatments. The ornamental grasses differed in responsiveness with Miscanthus sinensis ‘Gracillimus’ showing little response until 8 WAT while Calamagrostis × acutifolia ‘Karl Foerster’ exhibited a 22% reduction in plant height at 2 WAT with a 1 mg/L Concise dip followed by a 31% height reduction and 26% reduction in shoot dry weight at 12 WAT. A 1 mg/L liner dip of Concise gave significant height reduction of Phlox paniculata ‘David’ and Rudbeckia fulgida var. sullivantii ‘Goldsturm’ through 8 and 10 WAT, respectively. Liner dips are an effective means of growth regulation that can reduce worker contact with the chemical solutions and provide baseline control of vigorous or hard-to-control herbaceous perennial crops.

CYCLANILIDE INCREASES BRANCHING OF HERBACEOUS PERENNIALS

Many herbaceous perennials would benefit from additional branching to provide fuller pots in shorter production times. Cyclanilide (Tiberon, OHP, Inc., Mainland, PA, USA), a new product recently labeled in the USA for branching of woody ornamentals, was evaluated on several herbaceous perennials over two seasons. Cyclanilide was applied as a foliar spray to established plants grown in 1.1-L pots filled with a peat-lite medium in late summer. Plant height and number of branches were determined at two week intervals after treatment (WAT). Cyclanilide improved the lateral branching of Phlox paniculata ‘Bright Eyes’ with an eight-fold increase in the number of lateral branches per plant at 6 WAT with 20 mg/L (control 2.2 vs. 20 mg/L 17.8 branches). Higher rates of cyclanilide did not further increase the number of lateral shoots but did increase the phytotoxicity symptoms. Echinacea ‘Ruby Star’ treated with 20 mg/L cyclanilide had twice the basal branches as the untreated control. Lateral branching of Coreopsis ‘Sweet Dreams’ was also doubled by treatment with 20 mg/L cyclanilide. However, even 20 mg/L cyclanilide resulted in unacceptable phytotoxicity damage. Therefore, the study was repeated in the spring with lower rates (0, 5, 10, 15, 20, 25, 30 mg/L cyclanilide) applied to three cultivars of Echinacea, ‘Sunrise,’ ‘Sundown’ and ‘Double Decker’, Phlox paniculata ‘Blue Boy’ and Coreopsis ‘Sweet Dreams’. Only Phlox showed a significant improvement in branching for these spring-planted and spring-treated crops. Although cyclanilide may increase branching of some perennials, phytotoxicity may limit its use for spring production, and there are obviously production issues that affect its efficacy.

FIELD PRODUCTION OF TEXAS NATIVE EVENING PRIMROSE (OENOTHERA SPP.) AS A SOURCE OF GAMMA LINOLENIC ACID

FIELD PRODUCTION OF TEXAS NATIVE EVENING PRIMROSE (OENOTHERA SPP.) AS A SOURCE OF GAMMA LINOLENIC ACID

FORM OF NITROGEN AFFECTS GROWTH OF CATHARANTHUS ROSEUS

Annual vinca [Catharanthus roseus (L.) G. Don] is intolerant of high fertility, cool temperatures, and wet soil conditions, making vinca difficult for growers to produce alongside other, more tolerant bedding plants. Our objective was to develop better recommendations for producers. Growth of `Grape Cooler' vinca was compared using different production inputs, including type of media (with or without bark), form of micronutrient source, and form of N. Optimal root and shoot dry weights occurred in peat-lite media with either sulfated or chelated micronutrients adjusted to pH 5.5. Root and shoot dry weights were greatest when high nitrate-N to ammonium-N ratio fertilizers were used. Root and shoot dry weights were negatively affected by high levels of ammonium-N in the fertilizer solution. Root development is the critical factor in the production of high-quality vinca. Our data suggest that root development may be optimized by using fertilizer products that have a high nitrate to ammoniacal nitrogen ratio. Micronutrients in the sulfate form also seem to enhance growth when medium pH is maintained near 5.5. Use of high-porosity, peat-based mixes appears to provide an optimal root growth environment.

Controlling Rhizoctonia solani using Quartenary Benzophenanthridine Alkaloids

There are many naturally occurring substances that have the potential to be adapted to modern pest control chemistry. Azadirachtin, an insect growth regulator, is one such naturally occurring compound that has been widely accepted in insect pest management. Quartenary benzophenanthridine alkaloids (QBAs) are known to be effective in the control of crop-damaging fungal diseases. QBAs can be isolated from plants in the Papaveraceae. Extracts of Macleaya cordata, a species rich in QBAs, were formulated for drench application to Cucumis sativa `White Wonder' seedlings. The seedlings were grown in a peat-lite medium using 10-cm plastic pots and inoculated with Rhizoctonia solani. Test formulations were prepared with and without QBAs and applied at 75, 150, and 300 ppm QBAs as a 100 ml/pot drench. The QBA formulations that provided effective control of Rhizoctonia solani lost 20% or fewer seedlings compared to the formulation without QBA, which lost more than 60% of the seedlings. Treated plants were evaluated confirming Rhizoctonia solani infection.

Soilless Growing Media Amended With Sugarcane Filtercake Compost for Citrus Rootstock Production

Seeds of sour orange (Citrus aurantium L.) and Cleopatra mandarin (C. reticulata Blanco) were sown in Speedling trays filled with mixtures (v:v) of 0, 25, 50, 75 or 100 percent sugarcane filtercake compost (a natural waste by-product of sugarcane processing mills; bagasse) and a peat-lite medium. Seeds sown in 100 percent compost resulted in lower total percent germination, but similar mean days to emergence (MDE), seedling heights, and shoot weights and lower root weights than the control (100 percent peat-lite medium). Media amended with 25, 50 or 75 percent compost resulted in similar total percent emergence, (MDE) and root weights, but taller seedlings with heavier shoots than the control. SPAD-502 chlorophyll meter readings, and leaf N, Ca and Zn contents were higher for seedlings produced in compost amended media than in 100 percent peat-lite medium. The results suggest that compost derived from sugarcane filtercake can be successfully utilized as an amended medium for citrus seedling rootstock production.

A Taste-test Comparison of Organic and Conventional Greenhouse Tomatoes

`Caruso' tomatoes were grown in a glass greenhouse in Winter and early Spring 1991. All plants were grown in 16-liter nursery pots. Half the plants were grown in a conventional peat-lite medium (Profi-mix) and were fertilized with synthetic water-soluble fertilizer containing micronutrients and (in ppm) 187 N, 46 P, 278 K, 177 Ca, and 48 Mg. The other plants were grown in a potting medium composed of 1 mature compost (chicken manure and leaves): 1 loam: 2 vermiculite (by volume); this medium was amended with 1.5 kg bone meal (2N–10P–0K) and 3 kg dolomitic lime/m3. The “organic” treatment was fertilized with a fish emulsion solution containing (in ppm) 150 N, 13 P, and 25 K. The experiment was repeated in 1992 with `Capello'. In both years, fruit were harvested around the half-ripe to three-quarters ripe stage. All insect control was with insecticidal soap and bio-control agents. A blind taste test was conducted on campus in both years. In 1991, of 70 participants, 73% preferred the “conventional” tomatoes, 20% preferred the organic tomatoes, and 7% expressed no preference. In 1992, of 105 participants, 67% preferred the “conventional” tomatoes, 24% preferred the organic tomatoes, and 10% expressed no preference.

MEDIA AMENDED WITH BROILER LITTER COMPOST DID NOT AFFECT POINSETTIA GROWTH

Organic wastes have the potential to contaminate ground and surface water supplies when overused in agronomic crop production. Poultry manure contains organic N and can be composted and partially substitute for fertilizer or peatmoss in plant production. Our objective was to determine the effects on growth of poinsettias `Freedom' and `Supjibi Red' grown in media amended with broiler litter compost (BLC). Media were developed to resemble a commercial peat-lite medium by blending BLC, peatmoss, and perlite, by volume (BLC: peat: perlite) at 1:3:4, 2:2:4, 3:1:4, and 4:0:4. Plant height, growth indices, number of fully developed bracts, and visual marketability rating were not affected by adding BLC to the media.

Micropropagation of Gas Plant (Dictamnus albus L.)

Abstract Gas plant.(Dictamnus albus L.) was successfully micropropagated from greenhouse-grown plants capable of flowering. Stems from initial spring growth were surface disinfested and two- node sections were placed horizontally on modified Murishige and Skoog medium with 1 μM (0.2, ppm) benzyladenine (BA). A dose response to BA at 1,5 and 10 μM (0.2, 1.1,2.3 ppm) indicated that the greatest number of usable microshoots was observed in cultures from horizontally placed explants treated with 1 μM (0.2 ppm) BA. These cultures initiated between 7.6 and 9.5 shoots per culture with approximately 70% of the shoots greater than 2 cm (0.8 in). Microcuttings rooted poorly in vitro even with indolebutyric acid in the medium. However, microcuttings rooted between 71 and 86 percent under ex vitro conditions. Microcuttings either untreated or treated with indolebutyric acid (5,000 or 10,000 ppm) as a quick dip produced 1.8 to 2.6 roots per rooted cutting after being directly stuck in a peat-lite medium (Metro-Mix or Promix) in cell packs under high humidity. Untreated microcuttings rooted at higher percentages (67 to 88%) in peat-lite media compared to perlite or vermitculite (25 to 58%). Rooted microcuttings were successfully acclimatized to greenhouse conditions by gradually reducing humidity.

899 PB 534 MICROPROPAGATION OF ILIAMNA REMOTA, KANKAKEE MALLOW

Kankakee mallow is an endangered herbaceous perennial that is indigenous to Kankakee County, Illinois. Stock plants were from seeds pretreated in 82°C water prior to greenhouse germination and growth. Nodal explants were disinfested and placed in vitro onto agar-solidified MS medium containing 0, 0.1, 1.0, 5.0, or 10.0 μM BA and 1.0 μM IBA. Axillary shoots grew and elongated best when the medium contained no cytokinin. BA tended to result in a rosette pattern of leaves. Within hours of placing the original explants in vitro and shortly after subsequent transfers were made (even when there was no cutting) a bright pink exudate appeared in the medium. The most vigorous cultures tended to form the most exudate. Microshoots were placed in a high humidity container in vermiculite wetted with water. Rooting was 50% without auxin. Plants were transplanted into pots containing peat-lite medium and successfully acclimatized to the greenhouse.

949 EFFECT OF IRON AND LIGHT IN TENSITY ON GROWTH AND CHLOROPLAST DEVELOPMENT IN C3 AND C4 TURFGRASSES

The influences of elevated iron concentrations in the nutrient solution and light intensity on growth and the chlorophyll and chloroplast development in Kentucky bluegrass (Poa pratensis) `Touchdown' (C3), creeping bentgrass (Agrostis palustris) `Penncross' (C3), and buffalograss (Buchloe dactyloides) (C4) were investigated. Plants established in peatlite medium in 11-cm pots were fertilized with a Hoagland solution containing various iron concentrations (0, 0.01, 0.1, 1, 2, 4, 6, 8, 10 mM Fe+2) under two different light regimes. Preliminary results indicated that no biomass reduction or toxic symptoms developed in buffalograss when grown with iron levels up to 8 mM under high light conditions. As Fe+' levels were raised, plants became progressively greener with both the chlorophyll-a and chlorophyll-b contents increased. In Kentucky bluegrass, the sizes of chloroplasts and grana stacks in the cell were larger when grown with 2 mM than 0.05 mM Fe+2 in the fertilizer solution. The interactions of iron concentration and light intensity on pigmentation and photosynthesis of the three species are currently being determined.

Forcing White Asparagus in Various Substrates under Cool and Warm Regimes

One-year-old crowns of `Jersey Giant' asparagus (Asparagus officinalis L.) were forced into spear production at 28C in darkness. Total spear fresh weight and number per square meter responded quadratically to the percentage of sand incorporated in Pro-Mix BX (PMX) peat-lite medium, with maximum yields at 25% to 75% (by volume) PMX. In a second study conducted at 22 and 28C, total spear fresh weight and number per square meter for 96 days of harvest were similar when grown in weathered, spent mushroom compost (SMC) or 1 PMX: 1 sand (v/v), but were lower than those grown in PMX. The lower temperature caused heavier individual spears, while the higher temperature stimulated earlier spear production. During the first month of harvest at 22C, the total number and fresh weight of spears in SMC were 11% and 17% less, respectively, than in PMX. SMC may be a low-cost forcing substrate for white asparagus.

MICROPROPAGATION OF GAS PLANT (DICTAMNUS ALBUS)

Gas plant is an elegant ornamental which blooms in early summer. It is commonly propagated by seed which is limited by a complex dormancy. Micropropagation was investigated as an alternative method for efficiently propagating gas plant. Rapidly growing two node stem pieces were taken from mature greenhouse grown plants, surface sterilized and placed in MS medium with 1 μM benzyladenine (BA). Shoot multiplication was studied using in vitro derived four node explants cultured on MS media containing BA at 0, 1, 5, or 10 μM. Explants cultured on BA at 1 and 5 μM averaged 3.9 and 5.6 shoots per explant respectively and a mean yield of 2.7 and 2.5 shoots greater than 2 cm in length. Explants cultured at 10 μM produced 5.7 shoots per explant with only 0.8 shoots greater than 2 cm in length. Microcuttings failed to root in vitro even in the presence of indolebutyric acid (IBA). Microcuttings directly stuck ex-vitro in a peat-lite medium root at 90% with 1.9 roots per cutting.

INTERIORSCAPE PLANTS-THE EFFECT OF FERTILITY SOURCE AND HYDROPHYLIC POLYMER ON EXTENDING WATERING TIME

Interiorscape conditions were used to compare plant growth and water use between a commercially produced medium with hydrophilic polymer and a traditional peat-lite medium. 15 cm pots of parlor palm and pothos were grown in either the medium with polymer or a peat-lite medium. Fertilizer treatments applied to both media included: 1.2 kg N/m3 Osmocote 14N-6.1P-11.6K and 500 ppm (mg/kg) N of Peter's 20N-8.7P-16.5K. Plant height, width, top fresh and dry weight, quality and foliage color were determined for parlor palm and top fresh and dry weight and quality were determined for pothos. Plants grown in the peat-lite medium receiving either liquid fertilizer or slow-release fertilizer were significantly greater in all parameters measured than those growing in the medium with polymer that received liquid fertilizer. Plants grown in the medium with polymer had greater growth and quality with the slow-release fertilizer than liquid fertilizer treatments. The number of days until watering was not extended in the medium with hydrophilic polymer.

EFFECT OF FERTILITY SOURCE AND LIME ON THE PERFORMANCE OF HYDROPHILIC POLYMERS USED WITH SEVEN FOLIAGE PLANT SPECIES.

Studies were undertaken to compare plant growth and water use in a new commercially produced media that contained a hydrophilic polymer combined with a traditional peat-lite media. Rooted cuttings of nephytis, spathiphyllum, parlor palm, pothos, corn plant, `Dallas' fern, and gold dust dracaena were planted into 15cm plastic pots containing either a peat-lite media or the media with hydrophilic polymer. Both mediums were amended with 2.4 kg/m3 gypsum and then treatments of 0, 1.5, or 3 kg/m3 of dolomitic limestone were added. Plant height, width, growth index, top fresh weight and dry weight were measured. Preliminary tests indicated that the media with the hydrophilic polymer performed better with slow-release fertilizer than a constant liquid fertilization program. Plant growth appeared to be optimum at the 0 or 1.5 kg/m3 rate of dolomite. Plants grown in the media with the hydrophilic polymer produced plants of comparable quality to those in the peat-lite media.

IRRADIANCE AND TEMPERATURE EFFECTS ON DEVELOPMENT OF BEGONIA SEMPERFLORENS-CULTORUM

Effects of temperature (18-32C), irradiance (0-4.3 mol day-1m-2), and pH (4.5-7.5) on germination of begonia were evaluated. Germination of 90-93% occurred at 18-24C and 79-83% at greater than 24C. There was no difference in germination between seeds receiving ambient irradiance conditions and seeds receiving 24hr supplemental irradiance (4.3 mol day-1m-2). Begonia did not germinate in the dark. On filter paper, no germination occurred at pH 4.5 or 5.0 while germination of 84 and 94% occurred within the pH range 5.5-7.5. In a peatlite medium, germination ≥80% occurred across all pH levels evaluated.Photosynthetic photon flux (PPF), day temperature (DT), and night temperature (NT) effects on vegetative development (3 true leaves to first flower) were determined. Plant height increased <2 cm as PPF level increased from 4.4 mol day-1m-2 to 12.15 mol day-1m-2. DT and NT influenced plant height, but as with PPF, the differences were only 1-2 cm. Neither average daily temperature (ADT) nor the difference between the DT and NT (DIF) affected plant height. Primary lateral shoot number increased as temperature and PPF increased.

PH Affects Seed Germination of Eight Bedding Plant Species

Seeds of eight commonly grown bedding plant species [Ageratum houstonianum Mill., Begonia × semperflorens Hort., Impatiens wallerana Hook., Lobularia maritima (L.) Desv., Petunia × hybrida Hort., Pelargonium hortorum L.H. Bailey, Salvia splendens F. Sellow, Tagetes patula] were germinated at pH values from 4.5 to 7.5 at 0.5 increments. Seeds were germinated in petri dishes on filter paper saturated with buffer solutions or in petri dishes containing a 50 sphagnum peat: 50 coarse vermiculite (peatlite) medium moistened with buffer solutions. Germination on filter paper was affected by pH for all species tested. Peatlite medium pH affected germination of all species tested, except Salvia splendens. Species response to similar pH values differed between the two germination procedures. Total percent germination of seeds germinated was less in peatlite medium than on filter paper.

Medium and Hydrogel Affect Production and Wilting of Tropical Ornamental Plants

Abstract Viterra hydrogel at rates of 0, 1.75, or 2.50 kg·m−3 was tested for the production of three tropical ornamental plant species in two or all of the three media. These were a commercial peat-lite medium (SUN), a medium consisting of equal volumes of peatmoss, bark, and sand (PBS), and a mix containing equal volumes of peatmoss and bark (PB). Codiaeum was grown in SUN and PBS, Dieffenbachia was produced in all three media, and Hibiscus was planted in SUN and PB. Codiaeum variegatum (L.) Blume ‘Norma’ and Dieffenbachia ‘Camille’ grew more and required a longer time to reach initial wilting when grown in SUN than PBS. Hibiscus rosa-sinensis L. ‘Brilliant Red’ had similar growth in SUN and PB. In general, hydrogel had no beneficial effect on plant growth in a greenhouse. Hydrogel extended the time required to reach initial wilting of C. variegatum by 3 days (from 24 to 27 days), but had no effect on Dieffenbachia. Leachate from PBS had higher pH and lower electrical conductance (EC) than that from SUN. Hydrogel had no effect on leachate pH, but decreased EC of the leachate for C. variegatum used at the 2.5 kg·m−3 rate and for H. rosa-sinensis at both rates.

Composted Waste as a Peat Substitute in Peat-lite Media

Abstract Sewage sludge, pharmaceutical fermentation residues, cranberry wastes, and food flavoring wastes that had been composted by in-vessel techniques were tested as substitutes for Canadian sphagnum peat in a Cornell peat-lite mix-A. Marigolds (Tagetes erecta L. ‘Lemondrop’) were grown in a medium containing 50% (by volume) vermiculite, and 0%, 10%, 20%, 30%, 40%, or 50% compost, with the remainder comprised of Canadian peat. Marigold growth was improved when any or all of the peat was replaced with composted sewage sludge. Except for media containing 40% and 50% composted food flavoring waste, plant growth in nonliquid fertilized media containing the other composts was equal or superior to conventional Cornell peat-lite mix. Except for media containing 50% pharmaceutical, 50% cranberry, or 40% or 50% food flavoring compost, plant growth was improved by supplemental liquid fertilizer. Improved growth was related to increased levels of plant nutrients, while decreased growth, at the highest proportions of compost, resulted from excessive NH4N, pH, or soluble salts. Differences in aeration, water holding capacity, and other physical media properties were small. We conclude that many types of organic wastes, composted by in-vessel techniques, can be used as a substitute for part or all of the peat in a conventional peat-lite potting media.